<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script type="text/javascript">
			var b = undefined == null;
			console.log(b);
			/* try{
				var msg = document.getElementById("msg").innerText;
				console.log(msg);
			}catch(error){
				console.log("异常");
			} */
		</script>
	</head>
	<body>
		<input type="text" id="msg" />
	</body>
</html>
